User manual MCINTOSH MC250

[. . . ] Your completely filled in application for a SERVICE CONTRACT must be postmarked within 30 days of the date of purchase of the instrument. To receive the SERVICE CONTRACT all information on the application must be filled in. The SERVICE CONTRACT will be issued when the completely filled in application is received at Mclntosh Laboratory Incorporated in Binghamton, New York. 1. Mclntosh will provide all parts, materials and labor needed to return the measured performance of the instrument to the original performance limits free of any charge. [. . . ] INPUT--STEREO OR TWIN AMPLIFIERS For stereo or twin channel operation it is not necessary to use the same impedance loudspeaker on each output. Simply connect each channel for the impedance desired. strip. Connect the right leads in the same manner on the RIGHT OUTPUT barrier strip. When connected as above the MC 250 operates as a 50 watt per channel stereo amplifier. MONOPHONIC OUTPUT-- CONNECTING TO BARRIER STRIPS When the MC 250 is to operate as a monophonic amplifier, the two channels are combined to produce a single 100 watt output. This chart lists the proper connections and interconnections for monophonic operation. Connect one speaker to the If the screw marked speaker LEFT-COM and the other impedance is: to: LEFT-4 2 ohms 4 ohms LEFT-8 8 ohms LEFT-16 For constant voltage 25 volts LEFT-16 for all of the output impedances and voltages. Connections are made in the following fashion: Solder the left channel leads If the between: impedance is: Pin 1 and 2 4 ohms Pin 1 and 3 8 ohms Pin 1 and 4 16 ohms For constant voltage 25 volts Pin 1 and 4 Solder the right channel leads between: Pin 5 and 6 Pin 5 and 7 Pin 5 and 8 Pin 5 and 8 When connected as outlined the MC 250 operates as a 50 watt per channel stereo amplifier. MONOPHONIC OUTPUT - CONNECTING TO THE OCTAL SOCKET Connect a wire between: LEFT-4 and RIGHT-4 LEFT-8 and RIGHT-8 LEFT-16 and RIGHT-16 LEFT-16 and RIGHT-16 If the impedance is: 2 ohms 4 ohms 8 ohms 25 volts CONNECT 2 and 6 3 and 7 4 and 8 4 and 8 Solder the leads to: 1 and 2 1 and 3 1 and 4 1 and 4 When connected as above the MC 250 operates as a 100 watt per channel monophonic amplifier. STEREO OUTPUT --CONNECTING TO THE OCTAL SOCKET The octal socket marked OUTPUT can be used When connected as outlined the MC 250 operates as a 100 watt monophonic amplifier. AC POWER: The MC 250 operates on 117 to 130 volt, 50/60 Hz. The amplifier will be turned on and off if its power cord is plugged in one of the auxiliary AC outlets on the program source. control Panel Information INPUT The input of the MC 250 has a two position switch to permit the amplifier to be used in any one of three ways: (1) As a monophonic 100 watt amplifier. (2) As twin 50 watt amplifiers used with an electronic crossover network, or as two completely separate amplifiers. (3) As a stereo amplifier used with a Mclntosh preamplifier or other high output stereo program sources. In either position of the input switch the input sensitivity is 0. 5 volts for full rated output. In the STEREO position each input is controlled by a GAIN control. The GAIN control allows signal sources of 0. 5 volt up to 30 volts to be connected without overloading the input to the amplifier. The MONO position of the input switch parallels the inputs of both amplifiers. When the outputs are properly connected the MC 250 becomes a 100 watt monophonic amplifier. The RIGHT/MONO GAIN control permits connecting signal sources up to 30 volts without overloading the amplifier's input. To operate the MC 250 as a 100 watt monophonic amplifier the INPUT switch must be in the MONO position and the OUTPUT must be properly connected for monophonic operation. OUTPUT The two barrier terminal strips marked LEFT OUTPUT and RIGHT OUTPUT provide stereo connections for the normal speaker impedances of 4 ohms, 8 ohms, and 16 ohms, or monophonic operation connections for 2 ohms, 4 ohms, and 8 ohms. The terminal strips may also be connected for a constant voltage output of 25 volts in either stereo or mono. OUTPUT (Octal Socket) The octal socket marked OUTPUT has stereo connections for 4 ohms, 8 ohms, 16 ohms, and 25 volts. [. . . ] This arrangement assures complete circuit reliability. Only Mclntosh gives you this degree of protection. There are three separate power supply sections, One positive and one negative high current supply is used for the output stages. The other positive supply is used for the driving amplifier stages. [. . . ]